A device for monitoring the acetylene production rate of an oil-immersed transformer based on a gas relay measuring component

Abstract

The present invention relates to the technical field of monitoring equipment for power transformers, and more specifically, to a device for monitoring the acetylene production rate of an oil-immersed transformer based on a gas relay measurement component. The device comprises: an observation window provided on the gas relay, the interior of which is oil-filled; a light source unit for emitting a laser beam into the interior of the gas relay. If a bubble group exists within the gas relay, the bubble group scatters the beam; a sensor unit for receiving the light signal scattered by the bubbles and converting it into an electrical signal; a machine vision unit for capturing a motion image of the bubble group; and a processing unit for processing the electrical signal obtained by the sensor unit and the related image obtained by the machine vision unit. The present invention utilizes the light source unit, the sensor unit, the machine vision unit, and the processing unit to cooperate with each other, thereby accurately monitoring the motion state of the bubbles and significantly improving the monitoring accuracy of the gas production rate.

Description

Technical Field

[0001] The present invention relates to the technical field of monitoring equipment for power transformers, and in particular to an acetylene gas production rate monitoring device for an oil-immersed transformer based on a gas relay measuring component. Background Art

[0002] Transformers are essential, critical equipment in power systems, and their operational stability is directly related to the safety and efficiency of the entire power network. Oil-immersed transformers are widely used in large-capacity substations due to their superior electrical performance and efficient heat dissipation. However, over long-term operation, deterioration of the electrical insulation and oil can lead to the generation of gases within the transformer. The generation rate and type of these gases are important indicators for assessing transformer health. Therefore, timely monitoring of gas generation in oil-immersed transformers is crucial to ensuring their safety and preventing major accidents.

[0003] Gas relays, widely used in transformer protection, can monitor gas generation and oil flow in real time, effectively detecting and recording transformer fault conditions. Typically, gas buildup within oil-immersed transformers is primarily caused by electrical faults (such as arc discharges and partial discharges), overheating (such as oil vaporization caused by excessive temperatures), and aging of internal insulation materials.

[0004] Currently, gas relays rely primarily on traditional gas accumulation monitoring methods, which determine the device's status by measuring the amount of gas accumulated or concentration changes. Monitoring the rate of gas generation within the transformer can promptly identify potential faults and anomalies, thus preventing more serious accidents. However, there are currently no devices that monitor gas generation.

[0005] For example, the invention patent with publication number CN110514948A discloses an online monitoring device for transformer on-load switches. This device addresses the current situation where there are no monitoring devices for transformer on-load switches. The device can intelligently detect gas and insulating oil in transformer on-load switches, and monitor and evaluate the operating status of transformer on-load switches in real time. The invention patent with publication number CN114001793B discloses a transformer oil conservator oil level detection device and method. Using a laser ruler in conjunction with a pressure gauge, the device can obtain the pressure of the pressure gauge at different distances from the transformer oil conservator to be tested. The liquid level of the transformer oil conservator to be tested can be directly calculated based on the different pressures and distances. This not only allows for accurate oil level detection, but also prevents maintenance personnel from climbing the transformer, reducing operational risks. Furthermore, the device can quickly detect the oil level of the transformer oil conservator, improving the efficiency of transformer oil conservator oil level detection. The invention patent with publication number CN 110068670A discloses a transformer insulating oil micro-water and hydrogen system detection device and detection method thereof, which uses multiple existing solenoid valves to obtain corresponding detection devices. Therefore, the measurement accuracy of the gas by this device needs to be improved. Summary of the Invention

[0006] Purpose of the invention: In order to overcome the shortcomings of the prior art, the present invention provides an acetylene gas production rate monitoring device for oil-immersed transformers based on a gas relay measuring component, which solves the problem of low accuracy in monitoring gas production in oil-immersed transformers.

[0007] Technical solution: The present invention provides an acetylene gas production rate monitoring device for an oil-immersed transformer based on a gas relay measuring component, the device comprising: a gas relay; the gas relay is provided with an observation window, and the interior of the gas relay is in an oil-filled state;

[0008] A light source unit is provided on one side of the gas relay; the light source unit is used to emit a laser beam into the interior of the gas relay. If a bubble group exists inside the gas relay, the bubble group scatters the beam;

[0009] A sensor unit is provided on the other side of the gas relay opposite to the light source unit; the sensor unit is used to receive the light signal scattered by the bubble and convert it into an electrical signal;

[0010] A machine vision unit is provided on the periphery of the gas relay; the machine vision unit is used to collect motion pictures of the bubble group;

[0011] Processing unit; the processing unit is used to process the electrical signal obtained by the sensor unit and the relevant image obtained by the machine vision unit, so as to obtain the gas production rate of the bubble and realize dynamic monitoring of the dynamic bubble group;

[0012] The sensor unit includes a Fourier lens, a filter and a CCD sensor. First, the Fourier lens receives the light beam emitted by the light source unit. Second, the light beam is focused and filtered by the filter. The center wavelength of the filter is set to be the same as the corresponding wavelength of the light source unit, thereby ensuring that the light intensity after filtering by the filter comes from bubble scattering. Finally, the scattered light intensity at different angles is collected by the CCD sensor and converted into electrical signals.

[0013] Further, including:

[0014] The sensor unit also includes a double-layer cascaded metasurface lens, which is arranged between the filter and the CCD sensor. The double-layer cascaded metasurface lens includes a first protective layer, a first intermediate layer, a second intermediate layer and a second protective layer in sequence. The first protective layer and the second protective layer are made of a material with high transmittance at the wavelength of the light source unit. The first intermediate layer is formed of an array of titanium dioxide nanocolumns or silicon nanocolumns, and the second intermediate layer is formed of an array of germanium nanocolumns.

[0015] Further, including:

[0016] The first protective layer and the second protective layer are made of materials with high light transmittance at the wavelength of the light source unit. If the wavelength of the corresponding laser in the light source unit is 1531 nm , then choose quartz, sapphire or calcium fluoride.

[0017] Further, including:

[0018] The long axis of the germanium nanocolumn is 1.2 , short axis is 400 nm .

[0019] Further, including:

[0020] The light source unit includes a laser and a laser beam expander. The laser is arranged between the adjustment rod of the gas relay and the heavy gas reed contact. The laser beam expander amplifies the diameter of the light beam emitted by the laser.

[0021] Further, including:

[0022] The machine vision unit includes a camera and a lighting device. The camera is arranged above the incident position of the laser, that is, between the gas relay adjustment rod and the open cup. The lighting device is arranged on the other side of the gas relay opposite to the camera.

[0023] Further, including:

[0024] The CCD sensor is placed at the same level as the focal plane of the Fourier lens, and the size of the light ring of the CCD sensor is determined.

[0025] Further, including:

[0026] The method for determining the light ring size of the CCD sensor includes:

[0027] The CCD sensor obtains scattered light intensity images incident from the light source unit at different angles;

[0028] use canny The operator edge detection extracts the speckle contour information in the image and uses the edge detection boundary points as the input pixel points of the least squares fitting circle to determine the center of the halo;

[0029] The annular size of the CCD sensor is designed according to the diffraction maximum principle, and then the light energy coefficient matrix in Mie scattering is obtained.

[0030] Further, including:

[0031] The ring size of the CCD sensor is designed according to the diffraction maximum principle, thereby obtaining a light energy coefficient matrix, including:

[0032] The corresponding halo size range is obtained according to the particle size range to be detected, thereby determining the maximum and minimum halo radius;

[0033] The particle size range is divided into logarithmic bins to obtain the halo size at different bin sizes;

[0034] The number of light rings is made consistent with the number of particle size bins, so as to obtain the light energy coefficient matrix according to the bin particle size and the light ring size corresponding to each ring, and the condition number corresponding to the light energy coefficient matrix under different numbers of rings is obtained, and the number of bins corresponding to the minimum condition number is taken as the final number of bins.

[0035] Further, including:

[0036] The particle size range is logarithmically divided into bins to obtain the halo size under different bin sizes, which is expressed as: ;

[0037] in, is the radius of the ring of the photosensitive element of the CCD sensor, is the particle bin diameter, and the number of haloes is n Number of particle size grades m Consistent, is the wavelength of the laser, f is the focal length of the Fourier lens.

[0038] Further, including:

[0039] The processing unit includes a host computer, which calculates the gas production rate according to the signal of the sensor unit and the image of the machine vision unit, and displays it on a display screen.

[0040] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0041] (1) The present invention uses a light source unit, a sensor unit, a machine vision unit and a processing unit to cooperate with each other, and obtains bubble movement data and images respectively through the CCD sensor receiving device and the high-speed camera in the sensor unit. After being analyzed and processed by the host computer, the movement state of the bubble can be accurately monitored, and even the bubble generation rate and particle size distribution can be obtained, which significantly improves the monitoring accuracy.

[0042] (2) The CCD sensor in the sensor unit of the present invention is installed at the same level as the focal plane of the Fourier lens, and the corresponding halo size of the CCD sensor is calculated based on the image it captures, so that the CCD sensor better meets the requirements of this application, thereby providing an accurate and effective basis for calculating the relevant data of the bubble.

[0043] (3) The sensor unit of the present invention also includes a Fourier lens, a filter and a double-layer cascade metasurface lens, wherein the Fourier lens realizes the focusing of the light beam, and the central wavelength of the filter is the laser wavelength, thereby ensuring that the received light intensity information comes from bubble scattering, and the role of the double-layer cascade metasurface lens is to eliminate light field distortion, enhance signal consistency, increase scattered light intensity, and increase signal-to-noise ratio, thereby adding a CCD sensor suitable for this application, and the four cooperate to realize high-sensitivity detection of bubbles in gas relays.

[0044] (4) The present invention uses a Fourier lens to focus the scattered light, and the numerical aperture of the Fourier lens is positively correlated with the focal plane angular resolution. The CCD sensor after the Fourier lens is combined with the annular partition can simultaneously record the scattered light intensity at multiple angles, thereby improving the angular resolution and being suitable for dynamic monitoring of dynamic bubble groups.

[0045] (5) The monitoring device of the present invention is a contactless monitoring device. All components are located outside the gas relay, which avoids the mechanical wear and pollution risks that may occur in traditional methods, further ensuring the stability and accuracy of monitoring; and greatly improves the monitoring accuracy and real-time performance of the gas generation rate of the oil-immersed transformer, enhances the fault warning capability, and has strong technical innovation and broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly describes the drawings required for use in the embodiments. It should be understood that the following drawings illustrate only certain embodiments of the present invention and should not be construed as limiting the scope of the present invention. Those skilled in the art can, without inventive effort, derive other relevant drawings from these drawings.

[0047] Figure 1 This is a schematic diagram showing the connections of the various units in the device for monitoring the acetylene production rate of an oil-immersed transformer based on a gas relay measuring component according to Example 1 of the present invention;

[0048] Figure 2 This is a schematic structural diagram of an acetylene production rate monitoring device for an oil-immersed transformer based on a gas relay measuring component according to Example 1 of the present invention;

[0049] Figure 3 This is a schematic structural diagram of the gas relay according to Example 1 of the present invention;

[0050] Figure 4 Schematic diagram of the acetylene production rate monitoring device for an oil-immersed transformer based on a gas relay measuring component according to Example 2 of the present invention;

[0051] Figure 5 This is a schematic diagram of the double-layer cascaded metasurface lens structure according to Example 2 of the present invention;

[0052] It includes: a gas relay 100, an open cup 1, a heavy hammer 2, a spring 3, a baffle 4, a first permanent magnet 5, a heavy gas reed contact 6, an adjusting rod 7, a light gas reed contact 8, and a second permanent magnet 9; a light source unit 200, a laser 201, a laser beam expander 202, a sensor unit 300, a Fourier lens 301, a filter 302, a CCD sensor 303, a double-layer cascaded metasurface lens 304, a first protective layer 3041, a first intermediate layer 3042, a second intermediate layer 3043, a second protective layer 3044, a machine vision unit 400, a high-speed camera 401, an illumination device 402, a processing unit 500, and a host computer 501. DETAILED DESCRIPTION

[0053] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the embodiments of the present invention. It should be understood that the described embodiments are only a portion of the embodiments of the present invention, not all of them. Generally, the components of the embodiments of the present invention described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations.

[0054] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0055] In order to solve the technical problems in the above background technology, Figure 1 This is a structural schematic diagram of an acetylene gas monitoring device for an oil-immersed transformer based on a gas relay provided in an embodiment of the present disclosure. The acetylene gas monitoring device for an oil-immersed transformer based on a gas relay is introduced in detail below.

[0056] The present application discloses an acetylene gas production rate monitoring device for an oil-immersed transformer based on a gas relay measurement component, and mainly comprises: a gas relay 100; the gas relay 100 is provided with an observation window that allows a light beam to pass through, and its interior is in an oil-filled state. The gas relay 100 includes oil inlet and oil outlet channels, and is connected to the oil-immersed transformer through the oil inlet and oil outlet channels, thereby allowing oil circulation and bubble transport.

[0057] The gas relay 100 in this embodiment is an open cup gas relay. This embodiment takes the QJ1-80 gas relay as an example. Its specific structure is as follows: Figure 3 shown.

[0058] It features a unique open cup 1 and baffle 4 design: an upper portion of the open cup 1 with a first permanent magnet 5, and a lower portion of the baffle 4 with a second permanent magnet 9. Under normal conditions, the open cup 1 remains tilted upward due to the buoyancy of the oil and the weight 2, keeping the permanent magnet away from the reed contact. In the event of a fault, the open cup 1 or baffle 4 loses balance, driving the permanent magnet close to the reed contact, triggering the protective action.

[0059] The principle of the gas relay consists of two parts:

[0060] Light Gas Protection: Under normal conditions, the relay is filled with oil. The light gas reaction cup 1 tilts upward due to the combined effects of the oil's buoyancy and the weight 2, keeping the first permanent magnet 5 away from the light gas reed contact 8, causing it to disconnect. When a minor fault occurs within the transformer, a small amount of gas accumulates in the upper portion of the relay, causing the oil level to drop. The cup becomes exposed, losing balance and falling around its axis, driving the permanent magnet 4 downward as well. This connects the reed contact and generates a light gas trigger signal.

[0061] Heavy Gas Protection: In the event of a severe fault, a large amount of gas generated creates a strong airflow and oil flow from the transformer tank toward the oil conservator. When the oil flow velocity reaches the set value, the impact force on baffle 4 overcomes the force of spring 3, forcing baffle 4 to the set position. At this point, the second permanent magnet 9 approaches the heavy gas reed contact 6, causing it to close, generating a trip pulse and opening the circuit breakers on each power supply side of the transformer.

[0062] like Figure 2As shown, a light source unit 200 is provided on one side of the gas relay 100, which is the part of the observation window; the light source unit 200 is used to emit a laser beam into the gas relay 100. If there is a bubble group inside the gas relay 100, the bubble group scatters the beam. The bubbles are generated when the oil-immersed transformer fails and then migrate into the gas relay.

[0063] In this embodiment, the light source unit 200 includes a laser 201 and a laser beam expander 202, wherein the power of the laser 201 should be greater than 5mw. Specifically, the wavelength of the laser 201 is preferably 1531nm, the power is preferably 10mw, and the power of the laser is adjustable. The laser incident position is preferably between the adjustment rod 14 and the heavy gas reed contact 15, because the bubbles in this area are densely packed and the flow rate is relatively stable, thereby improving the measurement accuracy of the particle size.

[0064] In this embodiment, the laser beam expander 202 amplifies the diameter of the light beam emitted by the laser 201 to at least one million times, that is, the beam expansion diameter of the laser beam expander 202 should be greater than 10 mm. Specifically, the laser beam expander 202 used is preferably a beam expander that amplifies the diameter of the light beam emitted by the laser source to 15 mm.

[0065] In the present application, a sensor unit 300 is provided on the other side of the gas relay 100 opposite to the light source unit 200 ; the sensor unit 300 is used to receive the light signal scattered by the bubbles and convert it into an electrical signal.

[0066] Specifically, in this embodiment, the sensor unit 300 includes a Fourier lens 301, a filter 302 and a CCD sensor 303. First, the Fourier lens 301 receives the light beam emitted by the laser 201 in the light source unit 200. Secondly, the light beam is focused and filtered by the filter 302. The center wavelength of the filter 302 is set to be the same as the corresponding wavelength of the laser 201, thereby ensuring that the light intensity after filtering by the filter 302 comes from bubble scattering. Finally, the scattered light intensity at different angles is collected by the CCD sensor 303 and converted into electrical signals accordingly.

[0067] The CCD sensor 303 in the sensor unit 300 in this embodiment is installed at the same level as the focal plane of the Fourier lens 301, and the corresponding halo size of the CCD sensor 303 is calculated based on the image captured by it, so that the CCD sensor 303 is more in line with the requirements of this application, thereby providing an accurate and effective basis for calculating the relevant data of the bubble.

[0068] In this embodiment, the center wavelength of the filter 302 is preferably 1531 nm, the diameter of the Fourier lens 301 is preferably 55 mm, and the focal length is preferably 150 mm. A CCD sensor 303 is used to collect scattered light intensity at different angles. The pixel size of the CCD sensor 303 is preferably 5 μm. To improve focusing, the CCD sensor is preferably placed at the focal plane of the Fourier lens 301, as the light intensity at the focal plane is greater.

[0069] In this embodiment, the CCD sensor 303 collects scattered light intensities at different angles and converts them into electrical signals. Specifically, the light ring size of the CCD sensor 303 needs to be determined, including:

[0070] S1 Image preprocessing: The scattered light intensity image received by the CCD sensor from the light source unit 200 is subjected to a median filter to remove noise, making the scattered signal more uniform; the image is binarized to separate the speckle from the background;

[0071] S2 least squares method to determine the center: Use the Canny operator for edge detection to extract the speckle profile information, and use the edge detection boundary points as the input pixel points of the least squares method fitting circle to determine the center of the halo.

[0072] In this embodiment, Canny Edge detection is a classic edge detection algorithm in computer vision. The least squares method of fitting a circle determines the center and radius of the circle by minimizing the sum of the squares of the distances from all data points to the edge of the fitted circle. Specifically, in this embodiment, after the boundary points are detected using the Canny edge detection method, the coordinate point set corresponding to the boundary points is obtained, and then the least squares method is used to fit a circle to obtain the corresponding center coordinates and radius. The obtained center of the circle is used as the center of the light ring size of the CCD sensor 303.

[0073] S3 calculates the CCD halo size: specifically includes the following steps:

[0074] S31 obtains the corresponding light ring size range according to the particle size range to be detected, thereby determining the maximum ring radius and the minimum ring radius.

[0075] In this embodiment, the maximum radius and the minimum radius of the light ring are first obtained using the diffraction maximum principle.

[0076] S32 performs logarithmic binning on the particle size range to obtain the halo size at different bin sizes;

[0077] In this embodiment, the diffraction maximum principle is used again to design the annular size of the CCD sensor according to formula (1):

[0078] in, is the radius of the ring corresponding to each annular area of the CCD sensor 303, is the diameter of the particle size corresponding to the bin. Generally, the number of halo rings can be consistent with the number of particle size bins. n and m are the number of halo rings and the particle size, is the wavelength of laser 201, f is the focal length of the Fourier lens 301 .

[0079] S33 obtains the number of divided rings corresponding to the CCD sensor according to the logarithmic number of divided rings. In this embodiment, the number of light rings is consistent with the number of particle size divided rings, so as to obtain the light energy coefficient matrix according to the divided particle size and the light ring size corresponding to each ring, and obtain the condition number corresponding to the light energy coefficient matrix under different numbers of divided rings, and take the number of divided rings corresponding to the minimum condition number as the final number of divided rings.

[0080] In this embodiment, the number of rings can generally be taken to be consistent with the number of particle size grades. Specifically, when the maximum particle size grade is 5, the corresponding number of rings is also 5. At this time, the calculation is respectively 、 、 、 and Therefore, through the above steps, the center of the light ring of the CCD sensor 303, the number of light rings, and the radius corresponding to each light ring area are designed and obtained.

[0081] That is, in this embodiment, based on the calculation of the annular size of the CCD sensor, the light energy coefficient matrix T in Mie scattering can be calculated and constructed. Specifically, in a preferred embodiment of this embodiment, the elements in the light energy coefficient matrix T mean that the particle with a diameter D is n The scattered light energy of the ring and the light energy coefficient matrix can be obtained by the Mie scattering principle when the number of light rings and particle size are known.

[0082] The S4 ring size design comprehensively considers both test resolution and coefficient matrix properties. Generally, a greater number of rings results in higher measurement resolution, but also increased complexity. Furthermore, the optical coefficient matrix T is often ill-conditioned, an unavoidable mathematical problem in particle size inversion. Its essence is to pursue higher measurement resolution, and its only solution is to improve it.

[0083] This embodiment adopts a logarithmic binning method, which is beneficial to improving the matrix performance and obtaining more detection intervals within a small angle range.

[0084] This can be achieved by following the steps below:

[0085] S41 determines the measurement range: if the target particle size is to ;

[0086] S42 calculates the binning coefficient: according to the number of bins N, calculates the logarithmic step length. .

[0087] For example, if N=35, then .

[0088] S43 generates the bin diameter: according to the formula Generate bins, such as: ;

[0089] S44 is mapped to the torus radius:

[0090] According to the formula , each bin diameter Convert to the corresponding ring radius .

[0091] For ill-conditioned matrices, the condition number is a metric used to measure whether a matrix is "ill-conditioned" in numerical calculations. Generally speaking, the larger the condition number, the closer the matrix is to being singular, the greater the calculation error and the lower the accuracy. In this example, the condition numbers corresponding to the light energy coefficient matrices with 30-50 rings were calculated. The condition number corresponding to 40 rings was the smallest, and this was determined to be the number of rings.

[0092] In this embodiment, a machine vision unit 400 is provided on the periphery of the gas relay 100 ; the machine vision unit 400 is used to collect motion pictures of the bubble group.

[0093] Preferably, the machine vision unit 400 includes a high-speed camera 401 and an illumination device 402. The frame rate of the high-speed camera 401 should be greater than 800 frames per second. The high-speed camera 401 uploads the bubble motion pictures captured to the processing unit 500, which analyzes and processes them.

[0094] Furthermore, high-speed camera 401 records at a rate of 1000 frames per second and is connected to the host computer 501 of the processing unit 500 for image analysis. The high-speed camera 401 is preferably positioned above the incident position of the laser 201, i.e., between the adjustment rod 14 and the open cup 1. The lighting device 402 is preferably a light-emitting diode (LED) with an emission wavelength within the visible spectrum. The distance between the LED and the observation window of the gas relay 100 is preferably 110 mm.

[0095] Processing unit 500; the processing unit 500 is used to process the electrical signal obtained by the sensor unit 300 and the relevant image obtained by the machine vision unit 400, so as to obtain the gas production rate of the bubble and realize dynamic monitoring of the dynamic bubble group.

[0096] In this embodiment, the processing unit 500 includes a host computer 501 , which calculates the motion state, the total number of particle sizes, and the gas production rate based on the signals from the sensor unit 300 and the machine vision unit 400 , and displays them on a display screen.

[0097] This embodiment uses the host computer 501 to obtain the gas production rate, which mainly includes: obtaining light intensity information at different angles from the CCD sensor 303, calculating the bubble particle size and distribution; setting the image grayscale threshold for the image captured by the high-speed camera 401 to identify bubbles, obtaining the movement state of the bubbles based on two consecutive pictures, and obtaining the bubble rising rate, counting the bubbles in the field of view, and obtaining the gas production rate.

[0098] In this example, polystyrene particles of known sizes, such as 30 μm, 50 μm, and 70 μm, were used to verify the accuracy of the device's particle size and distribution measurements. Different gas flow rates were used to simulate the gas generation rate of a Buchholz relay under different fault conditions. The system's gas generation rate was calculated by combining the scattered light intensity distribution captured by a CCD with images of the bubble motion captured by a high-speed camera. Polystyrene particles of known sizes were preferred for simulating bubbles because they have good light transmittance and a fixed size, allowing for stable dispersion in liquids. Example

[0099] On the basis of Example 1, this embodiment adds a double-layer cascade metasurface lens 304 to the sensor unit 300, and the corresponding device structure diagram is shown in FIG. Figure 4 As shown, the double-layer cascade metasurface lens 304 is arranged between the filter 302 and the CCD sensor 303. Figure 5 As shown, the double-layer cascaded metasurface lens 304 includes a first protective layer 3041, a first intermediate layer 3042, a second intermediate layer 3043 and a second protective layer 3044 in sequence. The first protective layer 3041 and the second protective layer 3044 wrap the first intermediate layer 3042 and the second intermediate layer 3043. The protective layers are made of a material with high transmittance at the wavelength of the laser 201. The first intermediate layer 3042 is formed by an array of titanium dioxide nanocolumns or silicon nanocolumns, and the second intermediate layer 3043 is formed by an array of germanium nanocolumns.

[0100] In this embodiment, the first and second protective layers 3041 and 3044 provide support and protection. They should be made of materials with high transmittance at the wavelength of laser 201 to minimize attenuation of scattered light. For example, for the 1531nm laser used in this embodiment, quartz, sapphire, and calcium fluoride are suitable materials; for 532nm (green light), which falls within the visible light range, quartz and calcium fluoride are suitable materials; and for 635nm (red light), quartz or calcium fluoride are suitable materials. A double-layer cascaded metasurface lens enables high-sensitivity detection of bubbles in gas relays, while the sapphire layer serves as the outer protective layer, achieving near-infrared transmittance exceeding 95%.

[0101] Among them, the first intermediate layer 3042 is made of titanium dioxide TiO2 or silicon Si nanorod array, taking advantage of its high refractive index characteristics in the near-infrared band, such as the high refractive index corresponding to the wavelength of 1531nm. n =3.45, through the sub-wavelength size design of the nanorod, the continuous phase coverage of the incident light wavefront is achieved. For example, the phase delay of a silicon rod with a diameter of 800nm at a wavelength of 1531nm is .

[0102] The specific size design requires calculating the phase distortion based on the Fourier lens, filter, gas relay lens parameters, and typical values of oil flow turbulence used, and then designing the nanocolumn size based on the phase distortion value.

[0103] The first intermediate layer 3042 uses titanium dioxide TiO2 or silicon Si nanocolumn arrays to eliminate light field distortion: eliminate the spherical aberration and chromatic aberration of traditional lenses that cause distortion in the spatial distribution of scattered light, ensuring the spatial consistency of the Mie scattering signal; enhance signal consistency: reduce the scattered light fluctuations caused by oil flow turbulence through phase compensation, and reduce the particle size inversion error.

[0104] The second intermediate layer 3043 uses germanium nanorods, which generate a super-oscillating field through a non-periodic arrangement, breaking the diffraction limit. Traditional systems are limited by the diffraction limit of about 1μm, and the super-oscillating field can detect 0.2μm bubbles.

[0105] The germanium nanopillars have a long axis of 1.2 μm and a short axis of 400 nm. Their advantages include: the local enhancement effect of the superoscillating light field increases the Mie scattering intensity by 3-5 times, and by enhancing the signal-to-noise ratio of the scattered light intensity, the accuracy of the particle size distribution inversion is improved.

[0106] This embodiment uses a Fourier lens 301, a filter 302, a double-layer cascaded metasurface lens 304 and a CCD sensor 303 in combination, wherein the Fourier lens 301 is used for focusing, and the central wavelength of the filter 302 is the laser wavelength, ensuring that the received light intensity information comes from bubble scattering. The function of the double-layer cascaded metasurface lens 304 is to eliminate light field distortion, enhance signal consistency, increase the intensity of scattered light, and increase the signal-to-noise ratio. Finally, the light intensity information is input into the CCD sensor, which can provide purer data for the processing unit 500.

[0107] For illustrative purposes, the foregoing description has been made with reference to specific embodiments. However, the above illustrative discussion is not intended to be exhaustive or to limit the present disclosure to the precise forms disclosed. Numerous modifications and variations are possible in light of the above teachings. These embodiments have been selected and described in order to best illustrate the principles of the present disclosure and its practical application, thereby enabling those skilled in the art to best utilize the present disclosure and to utilize various embodiments with various modifications as appropriate for the specific application contemplated.

Claims

1. A device for monitoring the acetylene production rate of an oil-immersed transformer based on a gas relay measuring component, characterized in that: The device comprises: a gas relay; the gas relay is provided with an observation window, and the interior of the gas relay is in an oil-filled state; A light source unit is provided on one side of the gas relay; the light source unit is used to emit a laser beam into the interior of the gas relay. If a bubble group exists inside the gas relay, the bubble group scatters the beam; The light source unit includes a laser and a laser beam expander, wherein the laser is arranged between the adjustment rod of the gas relay and the heavy gas reed contact, and the laser beam expander amplifies the diameter of the light beam emitted by the laser; A sensor unit is provided on the other side of the gas relay opposite to the light source unit; the sensor unit is used to receive the light signal scattered by the bubble and convert it into an electrical signal; A machine vision unit is provided on the periphery of the gas relay; the machine vision unit is used to collect motion pictures of the bubble group; the machine vision unit includes a camera and a lighting device, the camera is provided above the incident position of the laser, that is, between the gas relay adjustment rod and the open cup, and the lighting device is provided on the other side of the gas relay opposite to the camera; Processing unit; the processing unit is used to process the electrical signal obtained by the sensor unit and the relevant image obtained by the machine vision unit, so as to obtain the gas production rate of the bubble and realize dynamic monitoring of the dynamic bubble group; The sensor unit includes a Fourier lens, a filter, and a CCD sensor. First, the Fourier lens receives the light beam emitted by the light source unit. Second, the light beam is focused and filtered by the filter. The center wavelength of the filter is set to be the same as the corresponding wavelength of the light source unit, thereby ensuring that the light intensity after being filtered by the filter is all scattered by bubbles. Finally, the CCD sensor collects the scattered light intensity at different angles and converts it into an electrical signal. The sensor unit also includes a double-layer cascaded metasurface lens, which is arranged between the filter and the CCD sensor. The double-layer cascaded metasurface lens includes a first protective layer, a first intermediate layer, a second intermediate layer and a second protective layer in sequence. The first protective layer and the second protective layer are made of a material with high transmittance at the wavelength of the light source unit. The first intermediate layer is formed of an array of titanium dioxide nanocolumns or silicon nanocolumns, and the second intermediate layer is formed of an array of germanium nanocolumns.

2. The device for monitoring acetylene production rate of an oil-immersed transformer based on a gas relay measuring element according to claim 1 is characterized in that: The first protective layer and the second protective layer are made of materials with high light transmittance at the wavelength of the light source unit. If the wavelength of the corresponding laser in the light source unit is 1531 nm , then choose quartz, sapphire or calcium fluoride.

3. The device for monitoring acetylene production rate of an oil-immersed transformer based on a gas relay measuring component according to claim 1, characterized in that: The long axis of the germanium nanocolumn is 1.2 , short axis is 400 nm .

4. The device for monitoring acetylene production rate of an oil-immersed transformer based on a gas relay measuring element according to claim 1, characterized in that: The CCD sensor is placed at the same level as the focal plane of the Fourier lens, and the size of the light ring of the CCD sensor is determined.

5. The device for monitoring acetylene production rate of an oil-immersed transformer based on a gas relay measuring component according to claim 4 is characterized in that: The method for determining the light ring size of the CCD sensor includes: The CCD sensor obtains scattered light intensity images incident from the light source unit at different angles; use canny The operator edge detection extracts the speckle contour information in the image and uses the edge detection boundary points as the input pixel points of the least squares fitting circle to determine the center of the halo; The annular size of the CCD sensor is designed according to the diffraction maximum principle, and then the light energy coefficient matrix is obtained.

6. The device for monitoring acetylene production rate of an oil-immersed transformer based on a gas relay measuring component according to claim 5, characterized in that: The ring size of the CCD sensor is designed according to the diffraction maximum principle, thereby obtaining a light energy coefficient matrix, including: The corresponding halo size range is obtained according to the particle size range to be detected, thereby determining the maximum and minimum halo radius; The particle size range is divided into logarithmic bins to obtain the halo size at different bin sizes; The number of light rings is made consistent with the number of particle size bins, so as to obtain the light energy coefficient matrix according to the bin particle size and the light ring size corresponding to each ring, and the condition number corresponding to the light energy coefficient matrix under different numbers of rings is obtained, and the number of bins corresponding to the minimum condition number is taken as the final number of bins.

7. The device for monitoring acetylene production rate of an oil-immersed transformer based on a gas relay measuring component according to claim 6, characterized in that: The particle size range is logarithmically divided into bins to obtain the halo size under different bin sizes, which is expressed as: ; in, is the radius of the ring of the photosensitive element of the CCD sensor, is the particle bin diameter, and the number of haloes is n Number of particle size grades m Consistent, is the wavelength of the laser, f is the focal length of the Fourier lens.

8. The device for monitoring acetylene production rate of an oil-immersed transformer based on a gas relay measuring element according to claim 1, characterized in that: The processing unit includes a host computer, which calculates the gas production rate according to the signal of the sensor unit and the image of the machine vision unit, and displays it on a display screen.

Images